Question. Describe the methods of selecting anterior teeth for an edentulous patient.
Answer:
The selection of anterior teeth is done to satisfy esthetic requirements. The anterior and posterior teeth must function in harmony and be anatomically and physiologically compatible with the surrounding oral environment.
Anterior Teeth Selection Methods
Anterior Teeth Selection – Size of Anterior Teeth
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Seven anatomic factors are used as guides to the selection of anterior teeth for size:
- Size of the face: The average width of the maxillary central incisor will be approximately one-sixteenth of the width of the face measured between the zygoma.
- The Trubyte Tooth Indicator is useful in determining the size of the maxillary central incisors. The combined width of the six maxillary anterior is slightly less than one-third of the bizygomatic breadth of the face. The face bow can be used as a caliper to record the bizygomatic breadth of the face.
- Size of the maxillary arch: The mold selector can be used to make measurements of the maxillary cast. Measurements are made from the crest of the incisal papilla to the hamular notches and from one hamular notch to the opposite hamular notch.
- The combined length of the three legs of the triangle in millimeters is used on the selector. When there is a discrepancy between face size and arch size the selection of anterior teeth should be done by face size.
- Incisal papilla and the cuspid eminences or the buccal frenum: Measure the distance from the distal of one cuspid eminence to the distal of the other and in the midline, the maxillary central incisors are situated labially to the papilla. The combined width of the six maxillary anterior teeth is determined in millimeters.
- Another method is to mark the occlusion rim at each corner of the lips. The marker is passed on a line parallel to the pupils of the eyes.
- The distance between the marks following the contour of the arch measured in millimeters is the combined width of the six maxillary anterior teeth.
- Maxillomandibular relations: Any disproportion in size between the maxillary and the mandibular arches influences the length, width, and position of the teeth.
- The contour of the residual ridges: The artificial teeth should be placed to follow the contour of the residual ridges that existed when the natural teeth were present.
- The vertical distance between the ridges: The length of the teeth is determined by the available space between the existing ridges.
- The lips: The labial surfaces of the maxillary anterior teeth support the upper lip. The labial incisal third of the maxillary anterior teeth supports the superior border of the lower lip and the incisal edges contact the lower lip at the junction of the vermilion border when the letter F is pronounced.
Anterior Teeth Selection Methods
Form of Anterior Teeth
Three factors are used as guides in the selection of anterior teeth for form.
1. Form of Anterior Teeth The form and contour of the face:
- The general outline of the tooth should conform to the general outline of the face in frontal view and the mesial or distal outline conform to the contour of the profile.
- The square, tapering, ovoid, and combinations of face forms help in selecting the tooth form. By using a tooth indicator on the patient’s face, face form as square, square tapering or ovoid can be assessed from the relationship of the face form with the vertical lines of the indicator.
- A profile is observed by checking the forehead, the base of the nose, and the point of the chin. If in line, the profile is straight.
2. Form of Anterior Teeth Sex:
Curved facial features are associated with femininity and square features are associated with masculinity.
3. Form of Anterior Teeth Age:
As age progresses the lips lose their curves and the teeth wear at the incisal edges and interproximal surfaces. The labial surfaces seem flatter and the outline form appears squarer.
Anterior Teeth Selection Methods
Form of Anterior Teeth Color or Shade of Anterior Teeth
- Shade is the degree of darkness of color with reference to its mixture with black. The yellow is more prominent in the gingival third and the gray is more prominent in the incisal third. To check the shade, the patient’s mouth should not be opened too wide.
- White light after 10 o’clock in the morning and before two in the afternoon is preferred. The tooth and the shade guide should be viewed from a distance of six or eight feet and from different angles.
- Harmony should exist between the color of the teeth and the color of the skin, hair, and eyes.
- To check the size, form, and shades, the anterior and posterior teeth of both arches should be arranged in their anatomic positions on accurately adapted records or trial bases.
Anterior Teeth Selection Methods
Form of Anterior Teeth Composition of Material of Anterior Teeth
- Artificial teeth for complete dentures are made either of porcelain or processed acrylic resins. The porcelain teeth are either air-fired or vacuum fired. The vacuum fired is denser than the air fired.
- Porcelain teeth are hard to abrade and will retain their finish. Gold pins must attach the porcelain teeth to the supporting base mechanically.
- Although porcelain is brittle, its hardness and resistance to abrasion from foods and brushing make it the material of choice for esthetic purposes when space is available.
- Acrylic resin teeth are not as hard as porcelain and can be abraded more readily. The acrylic resin teeth can be bonded to the denture base without mechanical means. The commonly used one is a reinforced cross-linked acrylic tooth, which has better abrasion strength.
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